Lubricating oil composition



Patented Oct. 28, 1941 2,260,341 v LUBRICATING on. COMPOSITION John ESchott, New York, N. Y., ass ignor to [lide Water Associated OilCompany, Bayonne, N. J a corporation of Delaware No Drawing. ApplicationApril 5, 1938,

Serial No. 200,073

3 Claims.

This invention relates to the lubrication of internal combustionengines; and is particularly directed, although not restricted, tosatisfactory and improved lubrication in the Diesel type of enginewherein extreme service conditions of temperature and pressure areencountered. To the attainment of these and other ends, the inventionprovides and encompasses compounded liquid petroleum compositionsconsisting essentially of motor lubricating oil with aluminum stearateand butyl carbitol (hydroxy butyloxyethyl ether) as compoundingingredients. The compounded products retain substantially the viscosityand fiow characteristics of an oil, and thereby distinguish from othercompounded lubricants of the plastic flow type such as greases andso-called liquid greases.

Modern engine design has made lubrication of internal combustion enginesan increasingly difficult and specific problem. In high speed units andespecially in Diesel engines lubrication is re- .quired under serviceconditions of such severity as to approach'the limit of safe andefficient operation with straight mineral oils. High temperatures andpressures, the catalytic effect of hot metallic surfaces continuouslycontacted under these conditions, accumulating concentration ofoxidizing agents, and auto-catalytic effect developing as deteriorationprogresses all contribute to lubricant. degradation. The lubricatingcapacity of the oil is, rapidly diminished by chemical and thermaldeterioration, and the products of deterioration create seriousoperating problems. Gummy or lacquer-like products, sludges, asphaltenesand coke are formed and the accumulation of such material has anaturally harmful effect upon engine parts and operation. Ring sticking,ineffective cylinder lubrication, increased wear, scoring ofcylinderwalls and like. trouble results, and frequent shutdown for cleaning,overhauling, and-often replacing of engine parts may be necessary. I

Accordingto the present invention, the fore- ,going difliculties -areobviated by lubricating inas lubricating composition comprising hydrocarbon lubricating. oil, aluminum stearate and butyl carbitol,hydrocarbon lubricating oil compounded with aluminumstearate and'butylcarnbito or the like are intended to designate and embrace any liquidhydrocarbon lubricating oil composition in which aluminum stearate andbutyl carbitol have been incorporated regardless of what complexcompound or mixture may actually exist in the compounded product.

The exact chemical mechanism of mineral oil deterioration in internalcombustion engine service is not clear although authorities havereasonably concluded that such phenomena as polymerization, oxidationand thermal decomposition are predominant factors. It is not intended,however, to limit or attempt an explanation of results attendinglubrication of internal combustion engines with the compounded oil ofthe invention on the basis of these or other theories. Results marking adistinction between success and failure in engine performance andlubrication are sufiicient evidence that the compounding of aluminumstearate and butyl carbitol with a quantity of steel wool may serve toprovide anindex. Sludge values do not seem to have particularsignificance but the character of the oxidation products at the end ofa; 70 hour run at 341 F. is an indication of conditions that may beexpected in engine service. Good Diesel "engine lubricants generallygive a clean tube without resinous or gummy products adhering to thewalls. If the sludge is sticky, gummy and unfilterable, the probabilityis that the oil willof compounded lubricants according to the pres entinvention, actual lubrication of engines both of the spark ignition and.of the compression ignition type was relied upon 'as the significantcriterion. Collateral indications were obtained with the Indianaoxidation test and with the modified form of this in which the test iscarried out in the presence of a weighed quantity of steel wool. In alltest operations, comparison was with blank runs in which straightmineral oil as usedin the compounding of a given lubribrication.

The compounding of aluminum stearate and butyl carbitol with ahydrocarbon motor oil intended for service, in the lubrication ofinternal combustion engines gave consistently improved results in alltests. In both automotive and Diesel engine service ring sticking andrelated difllculties were substantially to entirely eliminated, with thelubricant continuing to perform its lubricating function satisfactorilyover extended test periods under rigorous operating conditions. Goodgeneral engine condition was observed upon inspection at the terminationof the tests. In comparative test runs, straight mineral oils weremarkedly inferior, especially in Diesel engine service where relativelyshort runs resulted in badly stuck rings, inadequate lubrication andpoor general engine condition at shutdown.

The invention has general utility in the part of motor oil preparationand use. The base stock which is compounded as disclosed herein maycomprise any hydrocarbon lubricating oil and is not restricted toparticular crude petroleum sources or to particular degrees of refining.For example, aluminum stearate and butyl carbitol have been compoundedwith motor oil from Pennsylvania crude and with motor oil from anasphaltic-naphthenic California crude. In each case like benefit in theway of improved lubrication and elimination of ring sticking or likeengine trouble ensued. This is a particularly butyl carbitol. If thesoap-oil mixture is heated prior to butyl carbitol addition, viscositybuilds up and at about 190 Ill-220 '25. there is a marked gelling efiectwhich offers considerable resistance to agitation at this temperaturestage. As heating is continued, the gel thins out somewhat and themixture may be stirred without excessive power consumption. If desired,this pro; cedure may of course be used and butyl carbitol added afterthe mixture has been raised to elevated temperature.

It is' far more desirable, however, to introduce the butyl carbitol toan agitated soap-oil mixture before applying heat to the latter since inthis procedure no abnormal viscosity increase or gel formation occursduring the heat treatment and a fully fiuid mixture is maintainedthroughout. Apparently some reaction between the compounding agents oringredients is initiated immediately upon admixture, and this progressesas heat is applied.

As indicated above, the mixture of oil and both compounding ingredientsis heated at elevated temperature preferably 300 LEE-340 F. for

about two hours which is usually sumcient. If.

the heat treatment has been insuflicient for necessary cc mpleteness ofreaction, the oil upon cooling to room temperature will be turbid andadvantageous feature of the invention. "Many compounds proposed foraddition to petroleum oils are, as is well known, efiective orcompatible only with certain specific oils of prescribed crude c gln.

In general it is preferred that the base stock used in preparinglubricating compositions as herein be a motor ofl which has had a goodor superior degree of refining in the course of production. In thecaseof .naphthenic or as'phaltic base stocks a refining treatment withsulfuric acid or a combination of solvent extraction and acid treatmentis recommended. With Pennsylvania and like parafllnic' base stocks lessrigorbus refining treatment is necessary. One reason for the statedpreference is the conventionaldesirability of good or qualitylubricating oil simply from the viewpoint of superior capacity as alubricant. In a more pertinent aspect. however, I believe-that mycompounded lubricating composition has greater general utility ininternal' combustion engine service and gives better overall performancewhen well refinedbase stock tation being continued throughout thetreatment.

Aluminum stearate'is but sparingly soluble in mineral oil of lubricatingoil viscosity, and when added at room temperatures tendstofazglomeratehence the. desirability of thoroughly stirthe soap-oilmixture prior to addition of some further heating is required.Ordinarily, however, the indicated temperature and time of heatingsuffices to prepare a clear oil solution comprising the improved motoroil'of the invention. Additional heating not unduly prolonged does noharm.

With most oils a temperature above about 340 F. might be used if care isexercised but this is not regarded as particularly desirable since theobjectives of the invention are satisfactorily attained with greatercertainty and economy when the temperature does not exceed 340 F.Temperatures somewhat below 300 F, may be used successfully but withlower temperatures a longer period of heat treatment naturally isrequired.

Aluminum stearate of high purity is preferred. a

degree of difiicultly removable sedimentation upon prolonged storage ofthe compounded lubricating composition. This does not, however, seem tohave any particularly deleterious effect in engine service although theoil naturally is inferior in appearance to compounded oils which areclear solutions as are usually obtained in the preparationof lubricatingcompositions according to the invention.

' The mono-, di-, and tri-stearates of aluminum are marketedcommercially and are separately available. In each instance it isprobable that the product contains some impurity. percentage ticularaluminum stearate to be used in the prep aration of the compounded oil.For example. the

In most of our E have a higher viscosity and viscosity index than ofaluminum stearate and proportions by weight the motor oil used as a basestock. If the in- V crease in viscosity is reasonably limited, this is adistinct advantage, but the necessity of avoiding too great a deviationfrom given specifications for diiferentgrades of'motor oil makes itundesirable to have excessive viscosity increase in the compoundedproduct. I have found that advantages in the way of improved lubricationand engine operation are readily and consistently obtained withlubricating compositions. of the invention' when the viscosity of thecompounded product is increased only to a reasonable and desirabledegree. e

Proportions of aluminum stearate and of butyl carbitol to be used ascompounding ingredients for the purposes of the present invention willvary with oils from different crude sources and with differently refinedoils from the same crude source. In any given instance a degree oflatitude is available'in respect of desired proportions: and the amountsof each ingredient are selected with regard both to relative andconjoint effect. Where percentage of ash is a fixed specification for anoil to be used in particular service (as is sometimes specified forDiesel engine lubricants) this will determine the upper limit, ofaluminum stearate that can be used. More generally, the viscosity of-thecompounded product may be regarded as a limiting factor. Beyond about 2%or 3% of aluminum stearate, the viscosity is increased by the soap tosome degree independently of the butyl carbitol.

a Relative to each other, the proportion of butyl carbitol must besufficient to avoid more than moderate increase in viscosity due to theaddition of aluminum stearate. Butyl carbitol is soluble per se inhydrocarbon lubricating oil to a degree well in excess of therequirements of the present invention and may therefore be used incompounding proportion greater than that necessary for-conjoint actionwith aluminum stearate as herein. Some degree of benefit results fromthe presence of butyl. carbitol in mineral oils, and

an economical excess of this constituent consequently may be desirable.

As a general proposition, I have found that with good quality commercialaluminum distearate effective and suitable proportions of butyl carbitolfall in the range of about 5% to about 20%, and preferablyabout 8% toabout 15%, of the soap. Inmany experiments using a well refinedPennsylvania'base motor oil of S. A. E. 20 grade as a base stock I havefound that butyl carbitol as 10% of the soap e. g. aluminum stearate 1%and-butyl carbitol 0.1%,

of butyl carbitol equal to about 8-10% of the soap willprovide-lubricating compositions according to the invention, which are.entirely satisfactory for the majority of contemplated services. Inanygiven instance, however, the

desired proportions of materials may be readily determined by simpleexperiment, and specific illustrative disclosures herein'are notintended in v a limitative sense. 1

In my copending application Serial No. 404,720, filed July 30, 1941, asa continuation-in-part of the instant application, I have disclosed andclaimed certain generic aspects of the present invention, to wit, alubricating composition compounded with an aluminum soap of a saturatedfatty acid and a glycol or diglycol mono-ether of which the here claimedcomposition compounded with aluminum stearate and hydroxy butyloxy-ethylether is one species.

I claim:

1. Substantially liquid and non-stringy lubricating oil for internalcombustion engines operating at high sustained speeds and under extremeservice conditions of temperature 'and pressure such as may beencountered'in Diesel engine-lubrication, which comprises a hydrocarbonmotor oil of suitable viscosity for the intended service compounded withapproximately. 1% by weight of aluminum stearate and a quantity ofhydroxy butyloxy-ethyl ether, in the range of about 5% to 20% by weightof said aluminum stearate, sufficient to improve the lubricatingefiiciency of the oil, the ingredients of said compounded oil beingsubjected to a-heat-' engine lubrication, which comprises a hydrocarbonlubricating oil of suitable nominal viscosity for an intended servicecompounded and heated with small amounts of aluminum stearate andhydroxy butyloxy-ethyl ether in proportions ,such that thenormalviscosity of the oil is not increased beyond a reasonable and desirabledegree for its intended service,' the aluminum stearate being introducedin an amount not less than one percent. 3. Method of preparing motor oilcomposition suitable for the lubricating of internal combustion engines,which comprises compounding hydrocarbon lubricating oil ofsuitableviscosity for the intended service with approximately 1% both by weightbased on the weight of motor oil used in thecompounding) gives verysatisfactory results in every regard. Optimum proportions of butylcarbitol relative to aluminum stearate will vary when different motoroils comprise the base stock; and likewise will vary to some extentdepending upon the amount of soap. With larger proportions of soap thebutyl proportion generally should be larger. I believe the motor oilscompounded with about 1.0%-1.5% by weight by Weight of aluminum stearateand a quantity of hydroxy butyloxy-ethyl ether, in the range of about 5%to about 20% by weight of said aluminum stearate, sufficient to improvethe lubricating efiiciencyof the oil, and then subjecting the resultingmixture to a heat treatment at a temperature not, substantially lowerthan 300 F. for a period of time sufiicient to produce a resultingproduct which has substantially the viacosity and fluiditycharacteristics of the uncompounded oil. n JOHN E. SCHO'I'I.

